The present invention relates to a fishline guide member for installing to a fishing rod and guiding a fishline.
Conventionally, in fishing using a reel, a plurality of guide members in the form of ring are equipped to a fishing rod to guide a fishline and these guide members have been generally made of resin and/or metal. However, when fish is hooked, strong force is applied to the fishline and causes the fishline to slide on the guide members, requiring superb wear resistance of the guide members. Resin or metal guide members provide poor strength, wear resistance, slidability, and other properties, and tend to damage the fishline, and have problems of easy breakage during use in a comparatively short time.
Therefore, fishline guide members using ceramics in place of resin or metal are proposed. For example, in Japanese Patent Publication No. Sho 63-41532, there disclosed are fishline guide members made of zirconia ceramics and in Japanese Non-examined Patent Publication No. Hei 5-153887, there disclosed are fishline guide members made of silicon carbide ceramics, respectively. Because these ceramic fishline guide members provide high strength and excellent wear resistance and slidability, they can be used satisfactorily over a long period of time.
On the other hand, in the recent fishing industry, fishing using lures has been remarkably gaining popularity. In lure fishing, because the number of casting and rewinding of lures is so many and thin fishlines are used as well as light lures are used, load applied to fishlines increases. Therefore, in order to reduce this load, the frictional resistance between the guide members and the fishline must be further reduced.
Now, in the fishline guide members made of ceramics, the frictional resistance with fishlines is unable to be reduced, and the properties as required above were unable to be satisfied.
That is, because the conventional ceramic guide members are produced by forming the material comprising alumina (Al.sub.2 O.sub.3), zirconia (ZrO.sub.2), silicon carbide (SiC), and other main components as well as sintering aids, firing to achieve densification, and polishing the surface, the guide surface of the fishline is smooth and free of any pores. Consequently, the contact area between the fishline and the guide surface increases, and it is unable to prevent the frictional resistance from increasing.
To solve this problem, it is possible to consider, for example, to increase surface roughness of the guide surface of the ceramics fishline guide member or to decrease the contact area with the fishline by forming the guide member with ceramics porous material and allowing pores to exist on the surface. However, increasing the surface roughness of the guide surface causes the fishline to easily break, and making the guide member porous lowers the strength, creating another problem of easy breakage of the guide member when the fishing rod comes in contact with rocks, concrete, etc. when the fishing rod is being used.
Therefore, this invention relates to a fishline guide member with the fishline guide surface formed on the ceramics surface primarily composed of silicon carbide, which is characterized by having pores in the vicinity of the guide surface.
That is, the guide member proper is formed with dense ceramics virtually free of pores but with pores existing only in the vicinity of the guide surface, thereby reducing the contact area between the guide surface and the fishline and reducing the frictional resistance with high strength maintained.
This invention is characterized by 0.2-5.0% porosity in the vicinity of the guide surface, 10 .mu.m or less average porosity diameter, and 0.4 or less frictional coefficient with the nylon fishline.
In addition, this invention is characterized by silicon carbide ceramics that contain silicon carbide as the main component and Al.sub.2 O.sub.3, Y.sub.2 O.sub.3, and other metal oxides as sintering aids and that are formed by liquid-phase sintering.
This invention is also characterized by a manufacturing method of fishline guide member comprising a process for forming the material containing silicon carbide and metal oxides such as Al.sub.2 O.sub.3, Y.sub.2 O.sub.3, etc. into a specified profile, firing the material at a temperature ranging from 1800 to 2200.degree. C., decomposing the liquid-phase components on the surface to form pores, and then, polishing the surface to form the guide surface of the fishline.
That is, the silicon carbide ceramics containing metal oxides and liquid-phase sintered components are capable of having the liquid-phase components on the surface decomposed and pores generated only on the surface by adjusting the sintering conditions, and the fishline guide members as described above are able to be easily manufactured.